Newbie set up - what am I doing wrong?

We just switched over from Xfinity to Fiber and I got a UDR and a AP 7 In Wall and our signal and internet connection is worse.

We have tons of dropped packets and outages. ISP says everything is working on their end and hasn’t noticed any interruptions from the modem.

The UDR is downstairs in the basement so that’s I got the AP 7. Even on the same floor the WiFi signal is terrible. It’s been a disappointing start so I think I’m doing something wrong. The basic Xfinity router/modem provided better WiFi performance.

Any advice on placement or equipment? I’ve checked cables and swapped out “problematic ones”. Still week AP signal >76dbm even one or two rooms away.

Appreciate any insight or corrections to my set up!